I hope the bug report is correct here, I think this is a bug in the Qbs Project Manager module.
I have a big project, about 25 products, some dynamic libraries and some applications, divided in submodules. I use Qt Creator 3.0.1 and a qbs 1.2.0 build from the repository in mid January. I have 3 Qt Kits set up, Qt 4.8.5 with mingw, Qt 4.8.5 with MSVC2010 ans Qt 5.2.0 with mingw. Sometimes QtCreator crashes if I change the Kit. Most time it crashes if I switch to the third kit (doesn't matter which kit is the third. There is no error in the kits, I can build the project with each one).
I tried to figure out the problem, I build a debug version of the Creator and staret it in the debugger, according to the call stack, it crashes in the ProjectExplorer (callstack #4), the call stack leads to QbsProjectManager (callstack #12).
I attached the full callstack to this bug report.